Pipe threading

ABSTRACT

A pipe threading arrangement for connection to a service pipe ( 14 ) in a dwelling comprises a launch coupling ( 50 ) with a body portion ( 51 ) forming a chamber in which a parachute housing ( 60 ) is held. A stopper arrangement ( 30, 31 ) allows the coupling to be attached to the service pipe ( 14 ) whilst gas is present in both the service pipe and main. The housing includes a folded parachute-like device ( 62 ) attached to a line ( 66 ). A front portion of the parachute housing includes flexible guide ( 63 ) which allows the device to be manually lowered into a main pipe via the service pipe. A tube ( 65 ) is used to push the housing through the pipe. The tube is arranged to receive a jet of gas to separate the end with the guide attached and to inflate the parachute into the main where gas flow carries it along the main.

[0001] The invention relates to pipe threading to allow a cable orsimilar line to pass between two locations in the pipe.

[0002] Typically in order to provide a cable between two locations in anexisting main pipeline (e.g. gas main), it has been necessary toexcavate each site and add large and expensive fittings to thispipeline.

[0003] In our copending patent application PCT/GB99/00168 an arrangementis described which allows a parachute-like device to be launched betweentwo locations on the main pipe whilst keeping excavation to a minimum ifaccess is not readily available.

[0004] The present invention is concerned with an alternative pipethreading configuration which can be carried out between a main pipe andan auxiliary pipe typically within a customer's premises.

[0005] According to the invention there is provided a method ofthreading a cable between a relatively small bore service pipe at acustomer's premises at a first location and a second location on a mainpipe, the method comprising providing an access point in the servicepipe at the first location and an access point at the second location inthe main pipe, providing a retrieval device at the second location,launching a parachute-like device carrying a threading cable from theservice pipe, allowing the parachute to move to the second location bymeans of fluid flow through the main pipe and retrieving the parachutedevice or the cable attached at the second location to provide pipethreading between the two locations.

[0006] Further according to the invention there is provided a pipethreading apparatus including means for launching a parachute-likedevice attached to a cable from a relatively narrow bore service pipe ina dwelling at a first location to a second location in a main pipe underfluid pressure and means for retrieving the cable or parachute at thesecond location to provide pipe threading between the two locations.

[0007] Still further according to the invention there is provided a pipethreading apparatus for launching a parachute-like device including aclosed parachute chamber containing a collapsed parachute, elongateguide means attached to the chamber to assist in moving the chamberthrough bends in a narrow bore pipe towards a junction with a main pipeand means for applying fluid pressure to the chamber to launch theparachute from the chamber into the main pipe.

[0008] The invention will now be described by way of example withreference to the accompanying drawings in which:

[0009]FIG. 1 shows an existing gas main with an auxiliary service pipefor supplying a gas service to a customer's premises;

[0010]FIG. 2 shows an arrangement for gaining access to the service pipewhilst gas is present in this pipe;

[0011]FIG. 3 shows the stoppered service pipe following removal of theservice gas tap in one of a number of premises and the gas main accesspoint;

[0012]FIG. 4 shows the launch coupling about to be attached to theservice pipe;

[0013]FIG. 5 shows the introduction of the parachute arrangement intothe service pipe following removal of the stopper;

[0014]FIG. 6 shows the parachute housing and guide in more detailtogether with the launch gas supply;

[0015] FIGS. 7A-7F show stages in gaining access to the main to form thegas main access point as well as retrieval of the parachute device;

[0016]FIG. 8 shows the retrieval rod and frame carrying a stopping mesh;

[0017]FIG. 9 shows an alternative retrieval arrangement; and

[0018]FIG. 10 shows the removal of the launch coupling following thepulling through of the optical fibre cable.

[0019] An existing gas pipe arrangement is shown in FIG. 1 and includesa service pipe 14 which terminates in a customer's premises 36 and theother end is connected at junction 17 to a main gas pipe 20 having aninternal bore 21, the service pipe having a substantially smaller bore11. The main pipe 20 as well as part of the service pipe 14 is buriedbeneath the ground 15. The service pipe has two bends 12 and 13 belowground, in this example, before it rises vertically to the meter 18typically within a dwelling. A meter tap 16 is provided to shut off thesupply for safety or isolation reasons. Gas will typically be flowing inboth pipes and a governor adjacent the meter may typically also bepresent but it is omitted for the sake of simplicity.

[0020] The present configuration to be described allows for a line orcable to be passed between the small bore service pipe and the mainwhilst gas is present in the pipes without the need to excavate in theregion of the service pipe.

[0021] In order to gain access for threading purposes through theservice pipe, it is necessary to remove the meter whilst preventinginadvertent gas flow from the pipe which could be hazardous.

[0022] To achieve this step a mechanism as shown in FIG. 2 is employed.With the gas tap 16 in the closed position the meter 18 connection (seeFIG. 1) is removed and the FIG. 2 mechanism attached to the threadedportion 23 of tap 16.

[0023] The mechanism includes a housing 25 for a stopper 30 whichcomprises a flexible rod terminating in a number of rubber sealing discs31. A nut 26 can be tightened to compress a gland seal 27 so as toeffect a seal against the rod 30. The gland seal is typically formed ofboth metal and rubber discs. With this seal in place, the gas tap 16 canbe opened and gas in the service pipe 14 cannot escape due to the seal.

[0024] The rod is then pushed downwards to cause the end with the sealdiscs 31 to move through the bore of tap 16 into the service pipe. Oncein place, the checkpoint 28 allows for testing for any leakage. Assumingno leakage is present, the housing 25 can be removed. The stopper on therod remains in the service pipe. The rod tap 16 can then be removed fromthreaded portion 24 to gain clearer access to the service pipe.

[0025]FIG. 3 shows the stopper 30 in the accessible end of the servicepipe 14 within dwelling 36. Adjacent dwellings 37 and 38 will also haveservice pipes 40 and 41 respectively which can also be accessed in asimilar manner.

[0026] The threading arrangement now described will allow access fromany service pipe using the above technique to a convenient access point45 on the gas main.

[0027] A launch coupling 50 (see FIG. 4) includes a tubular body portion51 which can be coupled to portion 24 on the service pipe (e.g.compression fitting). Although the service pipe 14 is shown horizontallyfor illustrative purposes, it will in practice typically be vertical,with the body portion 51 correspondingly being in a vertical position.Within the body portion is located a flexible housing 60 in which isstowed a folded parachute-like device 62.

[0028] It can be seen that the launch coupling 50 also includes a secondbody portion 53 which extends at an angle from the main body portion andinto which the stopper rod 30 of FIG. 3 has been inserted. Once the rodis inserted, the portion 52 can be coupled to portion 24 of the servicepipe in preparation for the launch of the device 62. The rod 30 extendsexternally of the body 53 through a seal 54 surrounding an aperture inthe cap 55.

[0029] The parachute housing 60 has a flexible guide 63 extending from afront face and an elongate tube 65 extending from its rear end whichtube includes a thin flexible line 66 attached to the parachute. Thetube 65 is in sealed relation to the housing 60 by means of end seal 67.

[0030] The stopper rod can then be withdrawn into the chamber withinhousing 53, as shown in FIG. 5, to open the passageway into the servicepipe 14 without leakage of gas as the tube 65 abuts the seal 67A.

[0031] The mechanisms involved with the launch of the parachute aredescribed in more detail in FIG. 6.

[0032] The parachute 62 is formed of a suitable lightweight fabric andis folded and stowed within housing 60. It is attached to the line 66which extends from body 51 through flexible elongate tube 65. The tube65 is of sufficient length that it can pass through the entire length ofthe service pipe 14 to a position adjacent the junction of the serviceand main pipe. The line or wire 66 attached to the parachute is ofsufficient length to travel also along the main pipe to the retrievalpoint which could be 50 to 500 metres away, for example. Hence the lineis held on a reel 70 which will automatically be played out as theparachute moves along the main pipe due to gas flow. Cable 66 passesthrough running seal 69 to prevent gas escaping.

[0033] The flexible housing 60 is typically of corrugated plasticconstruction, the corrugations being arranged to allow the desireddegree of flexibility to be achieved. The housing terminates at the rearwith an end piece 74 to which the plastic tube 65 is affixed. The endpiece includes angle face 78 to assist in retrieval of the housingfollowing launch.

[0034] The front end 75 of the housing is arranged to be a push fit withthe body of the housing and has a curved face to assist in its movementthrough the pipe.

[0035] A guide extension 63 carries a weighted nose piece 73. The guideextension is formed from a helical spring which typically has agraduated resilience so that the end towards the nose piece is moreflexible than the portion nearer the end 75. This assists in enablingthe weighted nose piece to drop under gravity to ensure it will enterthe junction with the main and move downwards to prevent jamming at thisjunction.

[0036] Hence, when required, the guide 63 is pushed through the servicepipe by means of the external flexible tube 65 until it enters thejunction with the main. Then a jet of fluid (e.g. fuel gas or nitrogen)is made available from source 80 via button 81 to coupling tube 82 andthen to adaptor 83. This gas pressure separates end piece 75 and thisfalls away but is retained by cord 68 to prevent complete detachment. Asthis happens, the gas launches the parachute 62 and when it is in themain it is driven forward by the gas flow in the main 20.

[0037] The parachute travels through the pipe to the access point 90shown in FIG. 7A which will have been prepared prior to launch.

[0038] To form the access point 90, a drilling device 92 including adrill shaft 93 and drill bit/tap 96 is coupled to the pipe via a saddlevalve 113 which includes clamp chains 91. The housing 95 is sealed byseal 125 with the shaft 93 to allow drilling with pressurised gas in themain. The saddle valve 113 is open as shown to allow the drill to bepowered so as to drill through the wall of the main pipe and to form atapped hole therein (e.g. 1 inch BSP).

[0039] The drill is then partially withdrawn and the valve 113 closed toseal any gas entering.

[0040] The housing 95 can then be uncoupled, the drill removed and apipe holder 115 added with pipe 112 and placed over a stopper device111. The valve 113 is opened once the housing 95 is affixed and then thepipe holder with attached pipe and stopper is lowered through theaperture in the valve. On rotation of the holder 115 the threaded pipe112 is screwed into the main pipe wall. The pipe holder is sealed inrelation to the housing 95 and the stopper 111 prevents gas flow throughthe bore of pipe.

[0041] After checking for any gas leaks after screwing in the pipe, thehousing is removed to leave the pipe 112 with fitted stopper 111.

[0042] To this pipe, a special retrieval housing 110 is coupled as shownin FIG. 7C.

[0043] This accommodates the rod 114 in branch 130 and the main housingchamber 131 holds a retrieval mechanism comprising a rod portion 94 andhead portion 97 formed as a resilient metal frame carrying a mesh 98.

[0044] To prepare for the launch of the parachute from the service pipe,the rod 114 on stopper 111 is pulled generally upwards to cause thediscs 121 to move upwards into the branch chamber 130 so making the mainpipe available to receive the retrieval device. The running seals 116and 123 prevent any gas escape.

[0045] The lowering of the retrieval device, see FIG. 7D, is continueduntil it is within the bore of the main pipe 20.

[0046] The parachute 62 can then be launched via the service pipe and isstopped by the mesh 98 in head portion 97.

[0047] The rod 94 can then be pulled to withdraw the retrieval deviceand the parachute 62 therein together with the line 66 attached thereto.

[0048] As shown in FIG. 7E, once retrieved, the stopper is lowered andthe discs seal the aperture once again, the line 66 being trappedagainst the pipe wall and the resilience of the discs providing aneffective seal.

[0049] A cable, typically an optical fibre cable 99 can then be attachedto line 66 utilising fitting 110 to allow the optical cable to be towedback along the main to the service pipe and along the service pipeinside the dwelling.

[0050] The running seal 116 within fitting 110 can be selected to ensurea tight fit with the optical cable.

[0051] On sealing once again by the stopper 111 a seal cap 118 is thenadded in replacement to form an additional seal for the cable 99 withseal element 117.

[0052] A more permanent fitting will then typically be provideddependant on requirements.

[0053] This method has the advantage of providing an additional serviceinto the dwelling for TV, telephone, Internet, and other communicationswithout the need to excavate anywhere within the customer's premises sooffering a quick and inexpensive operation.

[0054] The retrieval mechanism is shown in more detail in FIGS. 8 and 9.

[0055] The rod 94 terminates in the retrieval mechanism which includes aresilient frame 97 which may be formed of a flat steel band which issufficiently flexible to be compressed when within the retrieval chamberbut will expand (shown expanded) when moved into the bore of the main.

[0056] In this first embodiment, the frame carries a flexiblelightweight mesh 98 which will not block the flow of gas in the mainpipe.

[0057] As explained above, in the extended position the parachute whenreaching the retrieval position will impact against the mesh 98 and canbe withdrawn through the special fitting 110 of FIG. 7E.

[0058] Although the retrieval mechanism of FIG. 8 employs a mesh, analternative version shown in FIG. 9 has only the flexible band 97 whichcan be employed for example where more than one access point is desiredin which case the intermediate access points would employ this rod withits band so that the parachute would pass through the band and move onto the next access point. During this operation the line or cable willhave threaded through the eye of the band 97 so on retrieval the linecan be pulled into the retrieval chambers of the intermediate accesspoints, so that the launch of the parachute only has to be carried outonce.

[0059] Once the optical fibre cable 99 has been pulled back through theservice pipe using the line previously attached to the parachute, thestopper previously employed with the FIG. 4 arrangement is againutilised, as shown in FIG. 10.

[0060] This stopper is pushed into place into the service pipe as in theFIG. 4 arrangement and the discs 31 are sufficiently resilient to holdthe cable 99 in sealed relationship to the inner wall of the servicepipe 14. At this stage the launch coupling 50 can be removed and asuitable adaptor for the service pipe and optical fibre cable addedprior to the replacement of the gas tap 16 and meter 18 of FIG. 1.

[0061] Although the stopper has been described in terms of a rod with anumber of sealing discs, the discs could be replaced by an inflatabledevice to effect the sealing; the rod being hollow to provide theinflatable source in such an arrangement.

[0062] The above method allows the addition of the cable to be made inthe dwelling without interrupting the supply of gas to other customersas the main continues to carry gas. The arrangement can cope with bendsin the narrow bore service pipe as well as the junction in the servicepipe and access requirements at the second location downstream. Theinterruption of availability of gas to an individual customer is kept tothe minimum as no excavation is required.

1. A method of threading a cable between a relatively small bore servicepipe at a customer's premises at a first location and a second locationon a main pipe, the method comprising providing an access point in theservice pipe at the first location and an access point at the secondlocation in the main pipe, providing a retrieval device at the secondlocation, launching a parachute-like device carrying a threading cablefrom the service pipe, allowing the parachute to move to the secondlocation by means of fluid flow through the main pipe and retrieving theparachute device or the cable attached at the second location to providepipe threading between the two locations.
 2. A method as claimed inclaim 1 wherein the launch step includes moving the parachute devicethrough the service pipe using guiding means from the access point to aposition adjacent a junction with the main pipe prior to launch.
 3. Amethod as claimed in claim 1 or 2 including the step of applying a fluidto a closed parachute chamber containing the parachute to open thechamber and to launch the parachute into the flowing fluid in the mainpipe.
 4. A method as claimed in claim 3 wherein the method includesproviding a sealable housing for holding the parachute chamber and apipe stopper device for selectively sealing the service pipe.
 5. Amethod as claimed in claim 4 including the step of providing a opticalfibre cable for attachment to the threaded cable at the second locationand pulling the optical cable through the main pipe into the servicepipe.
 6. A method as claimed in claim 5 including the step of sealingthe optical cable in the service pipe by means of a portion of thestopper device.
 7. A method as claimed in any preceding claim includingthe step of removing a gas meter attached to the service pipe to providethe access point in the service pipe.
 8. A method as claimed in anypreceding claim wherein an access point to the second location isprovided by forming an aperture in the main pipe and permanently fixinga duct thereto to allow a stopping mechanism and a retrieval mechanismto be utilised to access the main and retrieve the cable.
 9. A method asclaimed in claim 8 including the step of pulling an optical cable viathe access point utilising a sealed entry device.
 10. A pipe threadingapparatus including means for launching a parachute-like device attachedto a cable from a relatively narrow bore service pipe in a dwelling at afirst location to a second location in a main pipe under fluid pressureand means for retrieving the cable or parachute at the second locationto provide pipe threading between the two locations.
 11. Apparatus asclaimed in claim 10 wherein the launching means includes container meansfor the parachute and elongate guiding means for assisting the passageof the parachute to a position adjacent a junction with the main pipeprior to launch.
 12. Apparatus as claimed in claim 11 wherein theelongate guide means is resilient and includes weighted terminationmeans for ensuring the guide means has a tendency to extend downwards.13. Apparatus as claimed in claim 11 or 12 wherein the container meansincludes a closed parachute chamber and means attached thereto foropening the chamber and releasing the parachute in response to fluidpressure applied to the container.
 14. Apparatus as claimed in claim 11,12 or 13 including a sealable housing for holding the container meansand a pipe stopper device for selectively sealing the service pipe. 15.Apparatus as claimed in any one of claims 10 to 14 including housingmeans attachable to an entry point at the second location in the mainpipe, the housing means including means for holding a moveable stoppingdevice and means for holding a moveable retrieval device.
 16. Apparatusas claimed in claim 15 including seal means attachable to the housingmeans to allow an optical cable to pass through the entry point insealed relationship with the housing means.
 17. A pipe threadingapparatus for launching a parachute-like device including a closedparachute chamber containing a collapsed parachute, elongate guide meansattached to the chamber to assist in moving the chamber through bends ina narrow bore pipe towards a junction with a main pipe and means forapplying fluid pressure to the chamber to launch the parachute from thechamber into the main pipe.
 18. Apparatus as claimed in claim 17 whereinthe elongate means is configured to be biased so as to tend to angledownwards.
 19. A method of threading a cable substantially as describedherein.
 20. Pipe threading apparatus substantially as described hereinwith reference to the accompanying drawings.